Countdown in Python.

The program

Press Run to see what it prints. Change anything you like, then run it again.

count = 10
while count > 0:
    print(count)
    count = count - 1
print("Blast off!")

10
9
8
7
6
5
4
3
2
1
Blast off!

How it works

1. A while loop keeps repeating as long as its condition is true.
2. count = count - 1 makes the number smaller each time, so the loop ends. If you forget this line the loop never stops.
3. Compare it with a for loop: use for when you know how many times, and while when you do not.

Try this

• Count down from 20 in steps of 2.
• Print only the even numbers.
• Make it count up instead.

Stuck on an error? Read how to debug Python.